Adaptation to climate impacts ongroundwater resources in developed and developing countrieshas not received adequate attention. This reflects the oftenpoorly understood impacts of climate change, the hiddennature of groundwater and the general neglect of groundwatermanagement. Many developing countries are highly reliant ongroundwater. Given expectations of reduced supply in manyregions and growing demand, pressure on groundwaterresources is set to escalate. This is a crucial problem anddemands urgent action. This report addresses the impacts ofclimate change on groundwater and adaptation options. TheEarth's climate is projected to become warmer and morevariable. Increased global temperatures are projected toaffect the hydrologic cycle, leading to changes inprecipitation patterns and increases in the intensity andfrequency of extreme events; reduced snow cover andwidespread melting of ice; rising sea levels; and changes insoil moisture, runoff and groundwater recharge. Increasedevaporation and the risk of flooding and drought couldadversely affect security of water supply, particularlysurface water. Due to these pressures, as well as globalpopulation growth, demand for groundwater is likely to increase.